#
# make的主文件
#

# 文件夹
# OBJ用于存放编译出来的可重定位文件
OBJDIR := obj
# INC用于存放各种头文件(*.h)
INCDIR := include

# 编译以及日常工具
CC	:= gcc
# 汇编器
AS	:= nasm
# 静态库编辑器
AR	:= ar
# 链接器
LD	:= ld
# 复制文件
OBJCOPY	:= objcopy
# 反编译
OBJDUMP	:= objdump
# 查询可重定位文件符号表
NM	:= nm

DEFS	:= 

# gcc的相关命令参数
# $(DEFS) 定义一些可能的参数
# -O0 0优化，保证程序按照代码语义走而不被优化，方便调试
# -fno-builtin 静止使用gcc内置函数，具体查手册
CFLAGS	:= $(CFLAGS) $(DEFS) -O0 -fno-builtin
# -I 编译时去指定文件夹查找头文件
# -MD 一个黑科技暂时可以不需要了解，总之是在头文件依赖变动的时候能够及时更新target
CFLAGS	+= -I $(INCDIR) -MD
# -fno-stack-protector 禁止栈保护（金丝雀保护机制，内核代码扛不住）
CFLAGS	+= -fno-stack-protector
# -std=gnu99 规定编译的语言规范为gnu99
CFLAGS	+= -std=gnu99
# -fno-pie 不创建动态链接库
CFLAGS	+= -fno-pie
# -static 编译静态程序
# -m32 编译32位程序
CFLAGS	+= -static -m32
# -g 打开gdb调试信息，能够允许gdb的时候调试
CFLAGS	+= -g
# 一车的warning，在编译的时候可能会很有用
CFLAGS	+= -Wall -Wno-format -Wno-unused -Werror

# ld链接器的相关命令参数
# -m elf_i386 链接的格式为i386
LDFLAGS	:= -m elf_i386
# -nostdlib 不链接gcc的标准库，用库只能用命令行的
LDFLAGS	+= -nostdlib

# 获取gcc的库文件（除法取模会用到）
GCC_LIB	:= $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)

# 记录每个OBJDIR里存放的每个子文件夹
OBJDIRS	:=

# 保证all是第一个target，这样make的时候会先执行all
# all的依赖会在kern/Makefrag中填充
all:

.DELETE_ON_ERROR:

# xv6黑科技，获取编译命令，如果命令较新则重新编译所有文件
.PRECIOUS: 	$(OBJDIR)/.vars.%	\
		$(OBJDIR)/kernel/%.o $(OBJDIR)/kernel/%.d	\
		$(OBJDIR)/user/%.o $(OBJDIR)/user/%.d	\
		$(OBJDIR)/lib/%.o $(OBJDIR)/lib/%.d
$(OBJDIR)/.vars.%: FORCE
	@echo "$($*)" | cmp -s $@ || echo "$($*)" > $@
.PHONY: FORCE

include boot/Makefrag
include lib/Makefrag
include kernel/Makefrag
include user/Makefrag
include fs_flags/Makefrag

# FAT32镜像文件
IMAGE = $(OBJDIR)/a.img
BUILD_IMAGE_SCRIPT = build_img.sh

# added by mingxuan 2020-9-12
# Offset of os_boot in hd
# 活动分区所在的扇区号
# OSBOOT_SEC = 4096
# 活动分区所在的扇区号对应的字节数
# OSBOOT_OFFSET = $(OSBOOT_SEC)*512 
OSBOOT_OFFSET = 1048576
# FAT32规范规定os_boot的前89个字节是FAT32的配置信息
# OSBOOT_START_OFFSET = OSBOOT_OFFSET + 90
OSBOOT_START_OFFSET = 1048666 # for test12.img

# added by mingxuan 2020-10-29
# Offset of fs in hd
# 文件系统标志所在扇区号 = 文件系统所在分区的第1个扇区 + 1
# ORANGE_FS_SEC = 6144 + 1 = 6145
# 文件系统标志所在扇区 = $(ORANGE_FS_SEC)*512
ORANGE_FS_START_OFFSET = 3146240
# FAT32_FS_SEC = 53248 + 1 = 53249
# 文件系统标志所在扇区 = $(ORANGE_FS_SEC)*512
FAT32_FS_START_OFFSET = 27263488

# oranges文件系统在硬盘上的起始扇区
# PART_START_SECTOR = 92049
PART_START_SECTOR = 6144	# modified by mingxuan 2020-10-12

# 写入硬盘的起始位置
# INSTALL_PHY_SECTOR = PART_START_SECTOR + 951 # Why is 951 ?
INSTALL_PHY_SECTOR = 7095	# modified by mingxuan 2020-10-12
# assert(INSTALL_PHY_SECTOR > PART_START_SECTOR)

# 写入硬盘的文件大小
INSTALL_NR_SECTORS = 1000

INSTALL_START_SECTOR = $(shell echo $$(($(INSTALL_PHY_SECTOR)-$(PART_START_SECTOR))))
SUPER_BLOCK_ADDR = $(shell echo $$((($(PART_START_SECTOR)+1)*512)))

INSTALL_TYPE = INSTALL_TAR

INSTALL_FILENAME = app.tar

$(IMAGE): 	$(OBJDIR)/boot/mbr.bin		\
		$(OBJDIR)/boot/boot.bin		\
		$(OBJDIR)/boot/loader.bin	\
		$(OBJDIR)/kernel/kernel.bin	\
		$(BUILD_IMAGE_SCRIPT)		\
		$(OBJDIR)/user/$(USER_TAR)	\
		$(FS_FLAG_OBJFILES)
	@./build_img.sh $@ $(OBJDIR) $(OSBOOT_START_OFFSET)
	@dd if=$(OBJDIR)/user/$(USER_TAR) of=$@ bs=512 count=$(INSTALL_NR_SECTORS) seek=$(INSTALL_PHY_SECTOR) conv=notrunc
	@dd if=$(OBJDIR)/fs_flags/orange_flag.bin of=$@ bs=1 count=1 seek=$(ORANGE_FS_START_OFFSET) conv=notrunc
	@dd if=$(OBJDIR)/fs_flags/fat32_flag.bin of=$@ bs=1 count=11 seek=$(FAT32_FS_START_OFFSET) conv=notrunc

all: $(IMAGE)

clean:
	@rm -rf $(OBJDIR)

run: $(IMAGE)
	@qemu-system-i386		\
	-boot order=a			\
	-drive file=$<,format=raw	\
	-serial stdio

gdb: $(IMAGE)
	@qemu-system-i386		\
	-boot order=a			\
	-drive file=$<,format=raw	\
	-s -S				\

gdb-no-graphic: $(IMAGE)
	@qemu-system-i386		\
	-nographic			\
	-boot order=a			\
	-drive file=$<,format=raw	\
	-s -S				\

# 调试的内核代码elf
KERNDBG := $(OBJDIR)/kernel/kernel.dbg

monitor: $(IMAGE)
	@gdb                            	\
	-ex 'set confirm off'			\
	-ex 'target remote localhost:1234'	\
	-ex 'file $(KERNDBG)'			

disassemble: $(IMAGE)
	@$(OBJDUMP) -S $(KERNDBG) | less

# 黑科技时间，获取每个.c对应的头文件依赖
# 挺难整明白的，不建议一开始整明白，反正从xv6上抄的，不明觉厉
$(OBJDIR)/.deps: $(foreach dir, $(OBJDIRS), $(wildcard $(OBJDIR)/$(dir)/*.d))
	@mkdir -p $(@D)
	@perl mergedep.pl $@ $^

-include $(OBJDIR)/.deps

.PHONY: all clean run gdb gdb-no-graphic monitor disassemble